Rod system including at least two rods and connector device for rods

ABSTRACT

A rod system, in particular, for the spine, includes a first rod, a second rod, and a connector for connecting the first rod and the second rod. The connector includes a main body defining a first rod seat configured to hold the first rod in a fixed manner and a second rod seat configured to accommodate a second rod, and a fixation member and a closure member that are interchangeably mountable to the main body. When the fixation member is mounted to the main body, the fixation member is engageable with the portion of the second rod to hold the second rod in a fixed manner relative to the main bod, while when the closure member is mounted to the main body, the closure member is configured to hold the second rod to the main body in a slidable manner.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application claims priority to and the benefit of U.S.Provisional Patent Application No. 63/055,100, filed Jul. 22, 2020, thecontents of which are hereby incorporated by reference in theirentirety, and claims priority from European Patent Application EP 20 187183.7, filed Jul. 22, 2020, the contents of which are herebyincorporated by reference in their entirety.

BACKGROUND Field

The application relates to a rod system including at least two rods anda connector. Further, the application relates to a connector device forconnecting at least two rods. The rod system is applicable in thetreatment of spinal deformities, but can also be useful in degenerativespinal surgery, for example, in dynamic stabilization or hybridconstructs.

Description of Related Art

For the treatment of early onset scoliosis of the pediatric spine, useof growing rods is known. Such growing rods may be spinal implants fixedabove and below an abnormally curved portion of the spine to correct thecurvature in a first step to some extent. Thereafter, the rods areprolonged in further correction surgeries to adapt them to the growth ofthe spine.

Rod systems including at least two rods that are connected to each otherand that are used in various applications are known in the prior art.

For example, U.S. Pat. No. 9,339,307 B2 describes a bone fixation deviceadapted to be coupled to bone anchors that allows movement of rods topermit a screw-rod construct to lengthen in response to bone growth,without necessitating post-surgical installation adjustment of thedevice.

Moreover, U.S. Pat. No. 10,610,262 B2, describes a spinal distractionsystem including a bearing connector fastened to a fixated rod and asliding rod, wherein the sliding rod includes a spring and a stop ring.

US 2006/0233597 describes a connection member for coupling to one ormore structural rods, including a coupler body with recesses to receivethe rods and a cam screw which is configured to selectively vary a sizeof the rod receiving recesses to impart a frictional force on the rods.

SUMMARY

It is an object of the invention to provide a rod system including atleast two rods and a connector device for the rods that provide animproved or alternative way of treating various spine disorders,conditions, and/or diseases, in particular spinal deformities, and moreparticularly deformities in the pediatric or juvenile spine, or indegenerative spinal surgery, in particular in dynamic stabilization orhybrid construct applications.

According to an embodiment, a rod system, in particular for the spine,includes a first rod, a second rod, a connector for connecting the firstrod and the second rod, the connector including a main body having afirst rod seat configured to accommodate a portion of the first rod, thefirst rod seat having a first longitudinal axis, and a second rod seatconfigured to accommodate a portion of the second rod, the second rodseat having a second longitudinal axis, wherein the connector isconfigured to permit the first rod to be fixed to the main body andconfigured to permit the second rod to be selectively fixable to themain body or slidably connectable to the main body. When the second rodis slidable in the second rod seat, it can move in the axial directionof the second longitudinal axis. Also, rotation of the rod in the rodseat is possible.

The rod system may be applied in spine surgery as a correction deviceand/or a stabilization device.

The connector of the rod system has a low profile. This renders itparticularly suitable for applications where available space is reducedor limited, such as in pediatric applications. In addition, theconnector has a small width, which renders it compact and lightweight.

In a further development, the connector also includes one, preferablytwo, fixation members, one of which is configured to fix the first rodto the connector and the other one is configured to fix the second rodto the connector. Alternatively, the second rod can be kept slidingrelative to the connector main body. In a further development, a closuremember is provided which can be used instead of the fixation member whenthe second rod is intended to remain slidable. Thus, the rod systemforms a modular system that provides various methods of use.

According to an embodiment, a connector device for connecting at leasttwo rods includes a main body having at least a first rod seatconfigured to accommodate a portion of a first rod, the first rod seathaving a first longitudinal axis, a second rod seat configured toaccommodate a portion of a second rod, the second rod seat having asecond longitudinal axis, a fixation structure configured to fix thefirst rod to the main body, and an orifice configured to selectivelyreceive one of a fixation member or a closure member to either fix aninserted second rod or to close the orifice while permitting the secondrod to slide.

Such a connector device has a low profile, a compact shape, and providesa modular system with a plurality of options for use.

According to a still further embodiment, a connector device forconnecting at least two rods includes a main body having at least afirst rod seat configured to accommodate a portion of a first rod, thefirst rod seat having a first longitudinal axis, a second rod seatconfigured to accommodate a portion of a second rod, the second rod seathaving a second longitudinal axis, an orifice located between the firstrod seat and the second rod seat configured to receive a fixationmember, the fixation member including a screw with a head, preferably amonolithic screw with a head, wherein the head has a lower side that isconfigured to act on at least one of the first rod or the second rod toimmobilize the first rod and/or the second rod when the first rod and/orthe second rod are in the respective first and second rod seats.Preferably the lower side of the head is tapered, for example, conicallytapered.

The connector device has only a few parts and has a low profile. Also,it is possible to clamp or fix the two rods simultaneously with a singlefixation member. Therefore, the width of the connector device can bemade small.

In a further embodiment, at least one of the first rod seat or thesecond rod seat, preferably both rod seats, is/are configured toselectively receive pairs of rods having different diameters, andwherein each of the pairs of rods having different diameter is fixed inthe rod seat through clamping with the lower side of the fixation memberat at least three contact areas.

Such a connector device is configured to connect a first pair of rodseach having a first diameter or a second pair of rods each having asecond diameter different from the first diameter.

In a still further embodiment, the fixation member is configured to betilted in the orifice. Such a connector device is configured to fix tworods having different diameters simultaneously with the same fixationmember.

As used in the present specification and the appended claims, the term“rod” shall be understood as including any elongate member, regardlessof the cross-sectional shape. Specifically, a spinal stabilization rodas used herein, may have, for example, a substantially circular, oval,or angular cross-section. Such cross-section may vary along the lengthof the rod.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features and advantages of the invention will become apparentfrom the description of embodiments by means of the accompanyingdrawings. In the drawings:

FIG. 1 shows a perspective exploded view of a rod system according to afirst embodiment.

FIG. 2 shows a perspective view of the rod system of FIG. 1 in anassembled state.

FIG. 3 shows a top view of the rod system of FIGS. 1 and 2.

FIG. 4 shows a cross-sectional view of the rod system of FIGS. 1 to 3,the cross-section taken along line A-A in FIG. 3.

FIG. 5 shows a cross-sectional view of the rod system of FIGS. 1 to 3,the cross-section taken along line B-B in FIG. 3.

FIG. 6 shows a cross-sectional view of the rod system of FIGS. 1 to 3,the cross-section taken along line C-C in FIG. 3.

FIG. 7 shows a perspective view from a top of a main body of a connectorof the rod system of FIGS. 1 to 6.

FIG. 8 shows a perspective view from a bottom of the main body of FIG.7.

FIG. 9 shows a front view of the main body of FIGS. 7 and 8 in adirection of a longitudinal axis of one rod seat.

FIG. 10 shows a cross-sectional view of the main body of FIGS. 7 to 9,the cross-section taken along line D-D in FIG. 9.

FIG. 11 shows a top view of the main body of FIGS. 7 to 10.

FIG. 12 shows a cross-sectional view of the main body of FIGS. 7 to 11,the cross-section taken along line E-E in FIG. 11.

FIG. 13 shows a cross-sectional view of the main body of FIGS. 7 to 11,the cross-section taken along line F-F in FIG. 11.

FIG. 14 shows a perspective view of a fixation member of the rod systemof FIGS. 1 to 6.

FIG. 15 shows a side-view of the fixation member of FIG. 14.

FIG. 16 shows a closure member of the rod system of FIGS. 1 to 6.

FIG. 17 shows a side-view of the closure member of FIG. 16.

FIG. 18 shows a perspective view from a top of a sliding member of therod system of FIGS. 1 to 6.

FIG. 19 shows a perspective view from a bottom of the sliding member ofFIG. 18.

FIG. 20 shows a top view of the sliding member of FIGS. 18 and 19.

FIG. 21 shows a cross-sectional view of the sliding member of FIGS. 18to 20, the cross-section taken along line G-G in FIG. 20.

FIG. 22 shows a perspective exploded view of a rod system according to asecond embodiment.

FIG. 23 shows a perspective view of the rod system of FIG. 22 in anassembled state.

FIG. 24 shows a perspective view from a top of a main body of aconnector of the rod system of FIGS. 22 and 23.

FIG. 25 shows a perspective view from a bottom of the main body of FIG.24.

FIG. 26 shows a front view of the main body of FIGS. 24 and 25 in adirection along a longitudinal axis of one rod seat.

FIG. 27 shows a cross-sectional view of the main body of FIGS. 24 to 26,the cross-section taken along line H-H in FIG. 26.

FIG. 28 shows a top view of the main body of FIGS. 24 to 27.

FIG. 29 shows a cross-sectional view of the main body of FIGS. 24 to 28,the cross-section taken along line I-I in FIG. 28.

FIG. 30 shows a perspective view of a rod system according to a thirdembodiment in an assembled state.

FIG. 31 shows a perspective view of a rod system including only one rodaccording to a further embodiment.

FIG. 32 shows a cross-sectional view of the rod system of FIG. 31, thecross-section taken in a plane perpendicular to a longitudinal axis ofthe rod and extending through a center of a fixation member.

FIG. 33 shows a perspective view of another embodiment of a rod systemincluding only one rod.

FIG. 34 shows a cross-sectional view of the rod system of FIG. 33, thecross-section taken in a plane perpendicular to a longitudinal axis ofthe rod and extending through a center of a fixation member.

FIG. 35 shows a perspective view of a still further embodiment of a rodsystem.

FIG. 36 shows a cross-sectional view of the rod system of FIG. 35, thecross-section taken in a plane perpendicular to longitudinal axes of twoinserted rods and extending through a center of a fixation member.

FIG. 37 shows a perspective view of a still further embodiment of a rodsystem in an assembled state.

FIG. 38 shows a cross-sectional view of the rod system of FIG. 37, thecross-section taken in a plane perpendicular to longitudinal axes of twoinserted rods and extending through a center of a fixation member,wherein the rods each have a first diameter.

FIG. 39 shows a cross-sectional view of the rod system of FIG. 37, withtwo inserted rods each having a second diameter that is smaller than thefirst diameter of the rods shown in FIG. 38.

FIG. 40 shows a perspective view from a top of a main body of aconnector of the rod system shown in FIGS. 37 to 39.

FIG. 41 shows a perspective view from a bottom of the main body of theconnector of FIG. 40.

FIG. 42 shows a top view of the main body of the connector of FIGS. 40and 41.

FIG. 43 shows a cross-sectional view of the main body of the connectorof FIGS. 40 to 42, the cross-section taken along line J-J in FIG. 42.

FIG. 44 shows a perspective exploded view of a rod system of a stillfurther embodiment.

FIG. 45 shows a perspective view of the rod system of FIG. 44 in anassembled state.

FIG. 46 shows a cross-sectional view of the rod system of FIGS. 44 to45, the cross-section taken in a plane perpendicular to longitudinalaxes of two inserted rods and extending through a center of a fixationmember, wherein the rods have different diameters.

FIG. 47 shows a cross-sectional view of the rod system of FIGS. 44 to45, with two rods having a same diameter.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 2, a rod system according to a first embodimentincludes a connector including a main body 10 and at least a first rod100 and a second rod 101 that are intended to be connected by theconnector. The rod system further includes at least one, and optionallytwo fixation members 40, which may be identical. One of the fixationmembers 40 is configured to fix the first rod 100 to the main body 10.The other one of the fixation members 40 may be used to fix the secondrod 101 to the main body, if desired. Further optionally, the rod systemmay include a closure member 50 that is configured to close an orificein the main body 10 when the second rod 101 is intended to remainslidable. Sliding members 60 may also be part of the rod system thatfacilitate sliding of the second rod 101 in the main body 10.

The first rod 100 and the second rod 101 may be substantially identical.They may have a circular cross-section and preferably a smooth surface.However, the rods are not limited to such a design. Usually, the firstrod 100 and the second rod 101 are configured to be connected to boneanchors (not shown). Such bone anchors could be, for example, pediclescrews that are inserted into the pedicles of vertebrae.

The first rod 100 is configured to be connected to the main body 10 insuch a manner that the rod is fixed, or in other words immobilized, withrespect to the main body 10 by using the fixation member 40. The secondrod 101 can remain movable, specifically slidable, with respect to themain body 10, for example within the sliding members 60. The second rod101 may alternatively be immobilized using a second fixation member 40.Hence, the second rod 101 may be kept slidable or may be fixed dependingon a particular desired application. If second rod 101 remains slidable,the closure member 50 may be used to close the respective orifice.

Referring in addition to FIGS. 3 to 13, the main body 10 will bedescribed in greater detail. The main body 10 is preferably a monolithicpart that has a substantially flat top 11 and a substantially flatbottom 12 that are substantially parallel to each other and that definea height h of the main body 10. The top 11 and the bottom 12 areconnected via, for example, outwardly bulged cylindrical sides 13, 14,the distance between the outermost portions of which define a width w ofthe main body 10, as shown in detail in FIG. 4. The main body 10 furtherhas a front end 10 a and a rear end 10 b in a top view, as shown in FIG.3, a distance between which defines a length I of the main body. By theheight h, the width w, and the length I, a height direction, a widthdirection, and a length direction, respectively, are defined.

At a distance from each of the sides 13 and 14, there are a first rodseat 15 and a second rod seat 16, respectively, that each extend fromthe front end 10 a to the rear end 10 b completely through the main body10. The first rod seat 15 is configured to receive the first rod 100 andthe second rod seat 16 is configured to receive the second rod 101. Morespecifically, the first rod seat 15 is formed as a cylindrical channelwith an inner diameter that substantially matches an outer diameter ofthe first rod 100 so that the first rod 100 fits therein, for examplewith friction. The first rod seat 15 defines a first longitudinal axisI₁ which may be located at the center of the main body 10 in the heightdirection. The second rod seat 16 is also a cylindrical channel defininga second longitudinal axis I₂ which may also be located at the center ofthe main body in the height direction. A central portion of the secondrod seat 16 has an inner diameter that substantially matches an outerdiameter of the second rod 101 so that the second rod 101 fits therein.Adjacent to the front end 10 a and adjacent to the rear end 10 b, thesecond rod seat 16 has receiving sections 17 with a slightly greaterinner diameter than the central portion of the rod seat for receivingthe sliding members 60, respectively. Circumferential inner grooves 18are formed in the receiving sections at a distance from the front end 10a and the rear end 10 b, respectively, appropriate for receiving acorresponding projection of the sliding member 60. Thereby, it can beensured that the sliding members 60, once inserted, are held in thereceiving sections 17 and are prevented from falling out of the secondthe rod seat 16.

The longitudinal axis I₁ of the first rod seat 15 and the longitudinalaxis I₂ of the second rod seat 16 are arranged parallel to each otherand at the same height with respect to the top 11 and/or the bottom 12.As can be seen in the figures, the rod seats 15, 16 are substantiallyclosed around an inserted rod. Thus, an inserted rod iscircumferentially encompassed by the rod seat at least over a certainlength except at positions where the fixation member 40 acts onto therod.

Between the first rod seat 15 and the second rod seat 16, a firstorifice 19 and a second orifice 19′ are formed that serve forselectively receiving the fixation member 40 or the closure member 50.The first orifice 19 defines a central axis c₁ as shown in FIG. 5 thatextends perpendicular to the first longitudinal axis I₁ of the first rodseat 15 and perpendicular to the second longitudinal axis I₂ of thesecond rod seat 16. The first central axis c₁ of the first orifice 19 islocated at a distance from the rear end 10 b that is smaller than thedistance between c₁ and the front end 10 a. Moreover, the first centralaxis c₁ is closer to the first rod seat 15 than to the second rod seat16 in the width direction.

The first orifice 19 extends completely from the top 11 to the bottom12. Adjacent to the bottom 12, the orifice 19 includes a threaded bore20 for receiving a shaft of the fixation member 40 and adjacent to thetop 11, the orifice 19 has an enlarged space for receiving a head of thefixation member 40 in a countersink manner. The enlarged space has,adjacent to the threaded bore 20, a tapered portion 21 that taperstowards the threaded bore 20, and following the tapered portion 21, asubstantially cylindrical portion 22 which opens, preferably with asmall bevel 23, to the top 11. The tapered portion 21 and thecylindrical portion 22 intersect the first rod seat 15 at the sidefacing the first rod seat 15, such that a cutout 24 is formed thatprovides an opening between the first orifice 19 and the first rod seat15. Referring to FIGS. 5 and 12 in particular, the cutout 24 is locatedabove the center of the main body 10 in the height direction, so thatthe fixation member 40 can press from a position above the middle of thefirst rod 100 when the first rod 100 is inserted into the first rod seat15. On the opposite side of the cutout 24 in the width direction, thetapered portion 21 of the orifice 19 is spaced apart from the second rodseat 16, so that an inserted fixation member does not contact a secondrod 101 inserted into the second rod seat 16.

Referring now in greater detail to FIGS. 3 and 10, the second orifice19′ extends completely from the top 11 to the bottom 12 of the main body10 and defines a second central axis c₂. The second central axis c₂ ofthe second orifice 19′ extends perpendicular to the second longitudinalaxis I₂ of the second rod seat 16 and also perpendicular to the firstlongitudinal axis I₁ of the first rod seat 15. The second orifice 19′ iscloser to the front end 10 a than to the rear end 10 b of the main body10. Moreover, the second orifice 19′ is closer to the second rod seat 16in the width direction than it is to the first orifice. As a result, thecentral axes c₁, c₂ of the first and the second orifice 19, 19′,respectively, are offset in the width direction. Similar to the firstorifice 19, the second orifice 19′ includes a threaded bore 20 adjacentto the bottom 12 and an upper portion that has the cylindrical portion22 adjacent to the top 11 and an intermediate tapered portion 21sandwiched between them. The second orifice 19′ is close to the secondrod seat 16, such that the tapered portion 21 and the cylindricalportion 22 intersect the second rod seat 16, thereby forming a cutout24′ or opening between the second orifice 19′ and the second rod seat16, as best seen in FIGS. 11 and 13. By means of the cutout 24′, atapered portion 43 of the fixation member 40 is permitted to contact thesecond rod 101 when the second rod 101 is in the second rod seat 16. Thetapered portion 21 is above the second longitudinal axis I₂ of thesecond rod seat 16. Hence, an inserted fixation member 40 is configuredto press from an upper side of the second rod 101 on the second rod 101.At the opposite side of the cutout 24′ in the width direction, thesecond orifice 19′ is spaced apart from the first rod seat 15, so thatan inserted fixation member 40 cannot act onto the first rod 100.

Lastly, the front end 10 a of the main body 10 includes a slantedportion 10 c that may extend from a distance from the opening formed bythe second rod seat 16 in the front end 10 a to approximately a shortdistance behind or past the second central axis c₂ of the second orifice19′ in the length direction of the main body 10, as depicted in FIG. 11.By means of the slanted surface 10 c, material can be saved and theconnector can be made more compact.

The main body has a low profile, since above and beneath the first rodseat 15 and the second rod seat 16, only a minimum of necessary materialis present. Also, because the fixation members are placed into theorifices which are arranged one after the other in the length direction,while the action zones 24, 24′ of the fixation members 40 with the firstrod 100 and the second rod 101 have only a minimum necessary distance inthe width direction, the main body is very slim in the width direction.Finally, by means of the slanted portion 10 c at the front end 10 a, themain body can be constructed more lightweight.

Referring now in addition to FIGS. 14 and 15, the fixation member 40will be described. The fixation member 40 is in the form of a screwhaving a threaded shaft 41 and a head 42. The threaded shaft 41 isconfigured to cooperate with the threaded hole 20 of the first orifice19 and the second orifice 19′, respectively. The head 42 has a shapethat generally matches the shape of the upper portion of the firstorifice 19 and the second orifice 19′, respectively. More specifically,the head 42 includes a tapered portion 43 adjacent the threaded shaft 41that is configured to fit into the tapered portion 21 of the first andsecond orifice 19, 19′, respectively, and a cylindrical portion 44adjacent the tapered portion 43 that is configured to fit into thecylindrical portion 22 of the first and second orifice 19, 19′,respectively. A beveled portion 45 may be provided that is between thecylindrical portion 44 and a free end surface 42 a of the head 42. Inthe free end surface 42 a, a tool engagement recess 46 may be formed.Various shapes of tool engagement recesses may be conceivable, such as apolygon recess, a torx-shaped recess, any type of longitudinal grooves,or any other engagement structure. A length of the fixation member 40along its screw axis is such that the head 42 of the fixation member canbe fully immersed or countersunk into the upper portion of the first andsecond orifice 19, 19′, respectively, and that preferably the threadedshaft 41 does not protrude substantially out of the threaded bore 20.This further contributes to the low profile of the connector.

As shown in FIG. 5, when the fixation member is inserted into the firstorifice 19, the tapered portion 43, which is preferably aconically-tapered portion, is permitted to contact the first rod 100from an upper side thereof, i.e. from a side above the middle of therod, when the first rod 100 is in the first rod seat 15. Tightening thefixation member 40 increases the pressure onto the first rod 100, sothat the first rod 100 is immobilized in the first rod seat 15.Similarly, when the fixation member 40 is inserted into the secondorifice 19′, it can be fully immersed or countersunk therein, so thatneither the head 42 nor the threaded shaft 41 protrude out of the top 11or the bottom 12, respectively. The tapered portion 43 is configured tocontact the second rod 101 through the cutout 24′. Tightening thefixation member 40 in the threaded bore results in an increasingpressure onto the second rod 101 until the second rod 101 is immobilizedor fixed in the second rod seat 16.

Referring now to FIGS. 16 and 17, the optionally provided closure member50 is in the form of a screw having a threaded shank 51 that isconfigured to cooperate with the threaded bore 20 in the first andsecond orifice 19, 19′, respectively, and a head 52. The head 52 has alength in the axial direction of the screw such that the head canaxially fit or be immersed into the upper portion of the first andsecond orifice 19, 19′, respectively, as can be seen in particular inFIG. 6. The head 52 is tapered between the shaft 51 and substantiallythe free end surface 52 a, wherein the taper may be steeper than that ofthe tapered portion 43 of the fixation member 40. By means of this, thehead 52 can be prevented from extending through the cutout 24, 24′ ofthe first or second orifice 19, 19′ and therefore prevented fromcontacting the first or second rod. A small bevel 53 adjacent the freeend surface may also be formed. A length of the closure member 50 issuch that the closure member can be immersed in the second orifice 19′without portions extending out of the top 11 or the bottom 12. In thefree end surface 52 a of the head 52, a tool engagement recess 54 is cutout that may have any suitable tool engagement shape, such as a polygon,a torx-shape, or any longitudinal grooves or other suitable shape.

Referring now in greater detail to FIGS. 18 to 21, the sliding members60 are preferably identical parts. Each sliding member 60 is formed as asleeve with a first end 60 a, a second end 60 b, and a longitudinal slot61 extending from the first end to the second end. By means of the slot61, the sliding member 60 is compressible such that it can be insertedinto the receiving section 17 of the second rod seat 16. In thecompressed configuration, an inner diameter of the sliding member 60 isonly slightly greater than an outer diameter of the second rod 101 suchthat the second rod 101 can slide within the sliding member 60. An outerbase diameter of the sliding member 60 corresponds to an inner diameterof the receiving section 17 when the sliding member is inserted therein.At a distance from the second end 60 b, a circumferential protrusion 62is provided that fits into the groove 18 of the receiving section. Bymeans of this, the sliding member 60 is axially fixed in the receivingsection 17. Adjacent the first end 60 a, a circumferential protrusion 63is formed that tapers and narrows towards the first end 60 a. Thecircumferential protrusion 63 extends out of the second rod seat 16 atthe front end 10 a or the rear end 10 b of the main body 10 once thesliding member is in the receiving section 17. Thereby, furtherinsertion of the sliding member into the second rod seat 16 is alsoprevented. The sliding members 60 are assembled with the main body 10 insuch a manner that they are inserted into the second rod seat 16 withtheir second end 60 b being the leading end.

The main body, the first and second rods, the fixation member orfixation members, and the closure member are made of a bio-compatiblematerial, such as a bio-compatible metal or a metal alloy, or of abio-compatible plastic material. Suitable materials may be titanium orstainless steel, NiTi alloys, for example Nitinol, or plastics likepolyether ether ketone (PEEK) or poly-L-lactide acid (PLLA). The partsmay be made of the same or of different materials from one another.

The sliding members may be specifically made of a plastic material thatfacilitates sliding, such as PEEK or polyurethane. The sliding membersmay also be made of the same material as the other components of the rodsystem, and can be coated with a coating that facilitates sliding of thesecond rod therein.

In use, the rod system is connected with bone anchors, for example, twobone anchors that are inserted in vertebrae, for example, of differentmotion segments of the spine such that the rod system bridges therespective motion segments. The bone anchors may be, for example,monoaxial or polyaxial pedicle screws inserted into the pedicles ofvertebrae. In greater detail, the first rod 100 may be connected to afirst bone anchor at the side of the front end 10 a, and the second rod101 may be connected to a second bone anchor at the side of the rear end10 b of the main body 10. The first rod 100 may be connected to the mainbody 10 in a way such that only a small portion of the first rodprojects out of the rear end 10 b of the main body 10. Once fixed to thebone anchor, the first rod is immobilized relative to the main body 10by inserting the fixation member 40 into the first hole 19 andtightening the fixation member. Thereby, the slanted portion 43 of thehead 42 of the fixation member presses through the cutout 24 onto thefirst rod 100 to fix the same.

It shall be noted, that by means of adjusting the strength of tighteningof the fixation member 40, the frictional force holding the rod can beadjusted. For example, for the purpose of correction steps, a frictionhold that can be manually overcome may be sufficient, whereas for finalfixation the fixation member can be fully tightened.

The second rod 101 may be connected to the second bone anchor whileremaining slidable with respect to the main body 10. Due to the slidingmembers, the sliding is considerably facilitated. Hence, the second rod101 allows the distance between the first and the second bone anchor tocontinuously vary corresponding to the sliding of the second rod withrespect to the main body, and therefore, with respect to the fixed firstrod 100. In the second orifice 19′, the closure member 50 may beinserted to close the orifice so that the orifice can be maintainedsubstantially free from vessels or tissue growing into it.Alternatively, instead of closing the second orifice 19′ with theclosure member 50, another fixation member 40 can be inserted into thesecond orifice 19′ to clamp and fix the second rod 101 at a desiredaxial position with respect to the main body 10. When tightening thefixation member 40 , the tapered portion 43 presses through the cutout24′ onto the second rod 101 until the second rod is immobilized.

In various examples of use, a surgeon can selectively use either anotherfixation member 40 to fix the second rod 101 or a closure member 50 toclose the second orifice 19′. Keeping the second rod 101 slidable, therod system can be used, for example, as a growing rod system. It shallbe noted that alternatively, the second rod 101 can be fixed and thefirst rod 100 can be kept slidable or, alternatively both rods can bekept slidable. It may be advantageous to provide a stop at the slidingrod to prevent the sliding rod from falling out. Such a stop may be, forexample, a clamping ring around the free end of the sliding rod which isclose to the main body.

Thus, the stabilization system provides a modular system that permits amultitude of applications with sliding and/or fixed rods.

Referring now to FIGS. 22 to 29, a second embodiment of the rod systemwill be described. Parts and portions that are the same or similar tothose of the first embodiment will be marked with the same referencenumerals, and the descriptions thereof will not be repeated. The rodsystem according to the second embodiment differs from the rod system ofthe first embodiment mainly in that the first rod is permanently fixedto the main body of the connector using a pin 70. Functionallycorresponding to the first orifice in the first embodiment, a pin hole27 for receiving the pin extends from the top 11 completely to thebottom 12 and is arranged offset from the middle of the main body 10′ inthe width direction towards the first rod seat 15. The pin hole 27 has asize and is positioned at a position such that the pin hole intersectsthe first rod seat 15, as shown in particular in FIG. 27. In the lengthdirection, the pin hole 27 is formed approximately at the center of themain body 10′. A central axis of the pin hole 27 extends perpendicularto the first longitudinal axis I₁ of the first rod seat 15.

The first rod 100′ includes a substantially cylindrical recessed portion100 a that is at an axial position corresponding to the pin hole whenthe first rod 100′ is inserted into the first rod seat and projects onlyslightly out of the rear end 10 b. The pin 70 forms a first fixationmember that is configured to be inserted into the pin hole 70, therebyengaging the recessed portion 100 a of the first rod 100′ when the firstrod 100′ is in the first rod seat 15.

A third orifice 119 is formed in the main body 10′ between the secondorifice 19′ and the rear end 10 b. The third orifice 119 has a centralaxis that is perpendicular to the longitudinal axes I₁ and I₂ of thefirst and second rod seats 15, 16 and positioned in the width directionat the same position as the central axis c₂ of the second orifice 19′.The third orifice 119 is identical in shape to the second orifice 19′.Hence, there is a cutout 124 forming an opening between the thirdorifice 119 and the second rod seat 16. The pin hole 27 may be arrangedin the middle between the second orifice 19′ and the third orifice 119on the side facing towards the first rod seat 15.

In the rod system of the second embodiment, the first rod 100′ is fixedto the main body 10′ in a specific axial position. The fixation iseffected by the pin 70 engaging the recess 100 a of the first rod 100′.As the pin may be press-fit into the pin hole 27, the axial androtational fixation of the first rod 100′ is permanent during ordinaryuse of the rod system. Moreover, the rod 100 can also be welded to themain body 10′, so that the connection is non releasable.

In use, two fixation members 40 can be placed into the second and thirdorifice 19′, 119, respectively, so that an enhanced fixation can beachieved by using two fixation members. Alternatively, one fixationmember 40 and one closure member 50 may be used or two closure members50 may be used for the second and third orifices 19′, 119 to keep thesecond rod 16 slidable. It shall be noted that the orifices 19′, 119 canalso remain open, i.e. without inserting a closure member 50.

In a modified embodiment, the first rod 100 and the main body 10′ can bea monolithic part. They may be, for example, machined out of one pieceof material. In this modified embodiment, the pin is not needed.

Referring to FIG. 30, a third embodiment of the rod system will bedescribed. Parts and portions that are identical or similar to those ofthe first or second embodiments are indicated with the same referencenumerals, and the descriptions thereof will not be repeated. the firstrod 100′ is identical to that of the second embodiment, i.e. the firstrod has the recess 100 a for engagement with the pin 70. The main body10″ lacks the third orifice 119 of the second embodiment. As a result,the main body 10″ only has the pin hole 27 for engagement with the pin70 and one orifice 119 for receiving a fixation member 40 or a closuremember 50. The front end 10 a lacks the slanted portion 10 c so that thefront end 10 a is substantially parallel to the rear end 10 b over thewhole width. The first rod 100′ is fixed to the main body 10″ via thepin 70 which is press-fit into the pin hole 27. Optionally, the firstrod 100′ can be welded to the main body 10″. The second rod 101 can befixed via fixation member 40 or can slide in the second rod seat 16.

The rod system according to the third embodiment has an even morereduced size in the length direction. In a modified embodiment, thefirst rod 100′ and the main body 10″ can also be a monolithic part, sothat the pin is not needed.

Referring to FIGS. 31 and 32, a still further embodiment of a rod systemwill be described. The rod system includes a rod 200 which may beidentical to the rod 100 or 101 of the previous embodiments, and aconnector including a main body 1000 and a fixation member 40. The mainbody 1000 is a body with a top 11′, a bottom 12′, and sides 13′, 14′,wherein the sides may have a substantially cylindrical outer surface. Itshall be noted, however, that the overall shape of the main body can beany shape, for example, cuboid. In the top 11′, a single rod seat 150 isformed which is substantially cylinder segment-shaped for a circular rod200. The rod seat is open, such that the circular rod can be insertedfrom the top 11′. Laterally offset from the rod seat 150, an orifice 190is formed, a central axis c of which extends perpendicular to thelongitudinal axis I of the rod seat 150. The orifice 190 has a threadedhole 191 that is configured to receive the threaded shaft 41 of thefixation member 40. On the side facing away from the rod seat, theorifice 190 may have a tapered portion 192 for receiving the taperedportion 43 of the fixation member 40. On the opposite side, the insertedrod is accessible by the head of the fixation member 40. Morespecifically, the orifice 190 is at a position such that, when thefixation member 40 is inserted into the orifice 190 and tightened, thetapered portion 43 of the head 42 of the fixation member 40 contacts therod 200 from above and presses the rod 200 into the rod seat 150. As aresult, the rod 200 is fixed or immobilized only by tightening thefixation member. The rod system includes only a few parts of simplestructure. Moreover, the connector has a very low profile.

Referring to FIGS. 33 to 34, a still further embodiment of a rod systemis shown. The rod system differs from the rod system in FIGS. 31 and 32mainly in that the main body 1000′ includes a rod seat in the form of asleeve-like portion 150′ that may have a sleeve-like prolongation orextension 200 with a smaller outer diameter. The two portions 150′ and200 form a rod extension in which a further rod (not shown) can beinserted. Hence the rod seat is substantially closed around an insertedrod. An outer contour of the main body 1000′ in the portion around theorifice 190 may be substantially rectangular, with one side attached tothe sleeve-like portion forming the rod seat 150′. The upper portion ofthe orifice 190 intersects the rod seat portion 150′ such that a cutout124′ forms an opening that permits the tapered portion 43 of the head 42of the fixation member 40 to press on an upper portion of an insertedrod. A free end surface in the axial direction of the rod seat portion150′ may be open or closed. In use, tightening the fixation member 40against an inserted rod clamps and finally fixes the rod in the axialposition.

Referring to FIGS. 35 and 36, a still further embodiment of a rod systemincludes two rods 100, 101 having a same diameter, a main body 1000″,and a fixation member 40. The main body 1000″ has a top 11″, an oppositebottom 12″ which are substantially parallel, two outwardly bulgedcylinder segment-shaped sides 13″, 14″ joining the top 11″ and thebottom 12″, a front end 1000″a, and a rear end (not visible in theFigures). In the top 11″, two cylinder segment-shaped rod seats 150″,160″ are formed having longitudinal axes I₁ and I₂, respectively, thatare substantially parallel to each other. The rod seats 150″, 160″ areopen so that the rods can be inserted from the top 11″. In the center ofthe main body between the rod seat 150″, 160″, an orifice 190″ is formedthat has a threaded hole 191″. A length of the threaded hole 191″ issuch that, when the fixation member 40 is inserted with the threadedshaft 41, the fixation member can be tightened to press with the taperedportion 43 onto an upper side of the rods 100, 101 which are insertedinto the first and second rod seats 150″, 160″. With the fixation member40, both rods can be fixed simultaneously. The rod system has few parts,a simple structure, and a low profile.

Referring to FIGS. 37 to 43, a still further embodiment of a rod systemwill be described. Parts and portions that are identical or similar tothe previously described embodiments are marked with the same referencenumerals, and the descriptions thereof will not be repeated. The rodsystem is configured to be used with various sets of rods, wherein thesets differ with respect to the diameter of the rods. The main body1000″ is similar to the main body 1000″ of the previous embodiment,however, the rod seats 150′″, 160″ are configured to receive rods ofvarious diameters. For example, as shown in FIG. 38, the rod seats150′″, 160′″ can receive a pair of rods 100, 101 of the same firstdiameter and can alternatively, as depicted in FIG. 39, receive a pairof rods 100′, 101′ of the same second diameter that is smaller than thefirst diameter. As depicted in FIGS. 40 to 43, the main body 1000′″ hasa top 11′″, an opposite bottom 12′″, sides 13′″, 14′″ which may becylindrically-shaped and connect the top and the bottom, a front end1000″a, and a rear end 1000′″b. In the middle of the main body betweenthe rod seats 150′″ and 160′″, an orifice 190″ is provided for receivinga fixation member 40′. The first rod seat 150″ includes a cylindricalportion 150′″a and a substantially V-shaped portion 150′″b (seen incross-section), preferably with a rounded bottom that is connected tothe cylindrical portion 150′″a in a continuous manner. The sidewalls ofthe V-shaped contour may form an angle between 45° and 135°, preferablyaround 90°. The cylindrical portion 150′″a is closer to the center ofthe main body or closer to the orifice in the width direction, whereasthe V-shaped portion 150′″b is located closer to the side 13′″.Likewise, the second rod seat 160′″ includes a cylindrical portion160′″a arranged closer to the center of the main body in the widthdirection, and V-shaped portion 160′″b, preferably with a rounded bottomthat is connected to the cylindrical portion 160′″a in a continuousmanner and that is located closer to the side 14′″ than the cylindricalportion 160′″a is to the side 14′″. The shape of the cylindrical sectionand of V-groove section of both rod seats may be identical and mirrorsymmetrical to a plane extending through the orifice 190′″ in the heightdirection. The orifice 190′″ includes a threaded portion 191′″ adjacentto the bottom 12′″ and a tapered portion 192′″ adjacent to the top 11′″.In greater detail, the orifice 190′″ is configured to receive thefixation member 40′ which differs from the fixation member 40 in thatthe head 42 has an enlarged tapered surface 43′ and may have acylindrical portion 44′ with an axially reduced height.

In use, when a first pair of rods 100, 101 is used that has a firstdiameter which may correspond to the inner diameter of the cylindricalportions 150′″a and 160′″a of the rod seats 150′″, 160′″, respectively,the rods may each substantially fill the rod seat except a small portionin the ground region of the V-shaped portion. When the fixation member40′ is inserted into the orifice 190′″, the fixation member touches withthe tapered portion 43′ onto the upper side of both rods, while thethreaded shaft 41 may not extend fully into the threaded portion 191′″,as depicted in FIG. 38.

When a second pair of rods 100′, 101′ with a smaller diameter than thefirst diameter is used, the rods 100′, 101′ do not fully fill the rodseats in the cylindrical portion 150′″a, 160′″a, but rest on the flanksof the V-shaped portion 150′″b, 160′″b along substantially two contactareas that are substantially parallel to the longitudinal axes I₁, I₂ ofthe rod seats. Inserting and tightening the fixation member 40′ againstthe rods 100′, 101′ allows the fixation member 40′ to extend deeper intothe threaded portion 191′″, so that the tapered portion 43′ of the head42′ of the fixation member 40′ contacts the rods 100′, 101′ at aposition farther outward in the radial direction of the head. The rods100′, 101′ are firmly clamped along three contact areas, with two of thecontact areas in the V-shaped portion of the rod seat and the thirdcontact area at the tapered portion 43′ of the fixation member 40′.

Lastly, a still further embodiment of the rod system will be describedwith reference to FIGS. 44 to 47.

The rod system according to this embodiment differs from the rod systemaccording to the previous embodiment in that a pair of rods withdifferent diameters can be used and fixed simultaneously with a singlefixation member. A first rod 100″ has a smaller outer diameter comparedto a second rod 101″. The main body 1000″″ includes the first rod seat150′″ and the second rod seat 160′″ as in the previous embodiment. Thefirst rod 101″ is configured to be received in the first rod seat 150′″and the second rod 101″ is configured to be received in the second rodseat 160′″. The orifice 190″″ between the first rod seat 150′″ and thesecond rod seat 160′″ is configured to receive a fixation member 40″ anda pivot sleeve 80. The orifice 190″″ has, adjacent to the bottom 12′″, aspherical segment-shaped recess 193 which includes a region of thesphere with a greatest diameter, i.e. over the equator of the sphere.The spherical segment-shaped recess 193 is configured to receive thepivot sleeve 80. The pivot sleeve 80 includes a spherical segment-shapedouter surface 81 and an inner cylindrical threaded passage 82 that isconfigured to cooperate with the threaded shank 41″ of the fixationmember 40″. The pivot sleeve 80 further has an axial slot 83 thatrenders the pivot sleeve compressible and expandable. Adjacent to thespherical segment-shaped recess 193, a tapered, preferablyconically-tapered, portion 194 is formed in the orifice 190″″ thatwidens towards the top 11′″. The tapered portion 194 may have a smallerinner diameter adjacent the spherical segment-shaped recess 193 than aninner diameter of the spherical segment-shaped recess 193 adjacent thetapered portion. The tapered portion 194 permits the threaded shank 41″to be tilted in the orifice 190″″. Similar to the fixation member 40 ofthe first embodiments, the head 42 of the fixation member 40″ includes atapered section 43 and a cylindrical section 44.

The pivot sleeve 80 may be inserted into the main body 1000″″ bycompressing it so that it can snap into the recess 193, where the pivotsleeve may be held by friction. Thereafter, the rods 100″ and 101″ maybe placed in their respective rod seats 150′″, 160′″. Finally, thefixation member 40″ is inserted into the orifice such that its shaft 41″engages the threaded inner side 82 of the pivot sleeve 80. In thisconfiguration, the fixation member 40″ can be tilted to some extentaround its screw axis so that it can clamp both rods simultaneously,with the tapered portion 43 providing the third contact area for each ofthe rods that rest in the V-shaped portion of the rod seat,respectively.

In another mode of use, two rods 100, 101 of the same diameter are used,as shown in FIG. 47. In this case, the screw axis of the fixation member40″ may be in the zero position, i.e. is perpendicular to an axis thatextends along a width of the main body of the connector.

Modifications of the above described embodiments are also conceivable.The particular features, structures or characteristics of one embodimentmay be combined with those of the other embodiments in any suitablemanner to produce a multiplicity of further embodiments. Particularshapes of the elements are not limited to the specific shape shown inthe drawings, but may vary. While straight rods are shown, the inventionis not limited thereto. The rods may also have a curvature. Also, therod seats and their respective longitudinal axes may have a curvature.Moreover, the rods can have another cross-section. The shape of the rodseat may be adapted to the cross-section of the rod. The orifices mayalso be closed at the bottom. Only one sliding member may be sufficientthat may have any suitable shape. Also, the sliding members can beomitted.

For the bone anchoring elements that are not shown, all types of boneanchoring elements that are suitable for anchoring in a bone or avertebra and configured to be connected to a rod may be used.

While the present invention has been described in connection withcertain exemplary embodiments, it is to be understood that the inventionis not limited to the disclosed embodiments, but is instead intended tocover various modifications and equivalent arrangements included withinthe spirit and scope of the appended claims, and equivalents thereof.

What is claimed is:
 1. A rod system, in particular, for the spine,comprising: a first rod; a second rod; and a connector for connectingthe first rod and the second rod to one another, the connectorcomprising: a main body defining a first rod seat that extends along afirst longitudinal axis and that is configured to hold a portion of thefirst rod in a fixed manner, and a second rod seat that extends along asecond longitudinal axis and that is configured to accommodate a portionof the second rod; and a fixation member and a different closure memberthat are interchangeably mountable to the main body; wherein when thefixation member is mounted to the main body, the fixation member isengageable with the portion of the second rod to hold the second rod ina fixed manner relative to the main body; and wherein when the closuremember is mounted to the main body, the closure member is configured tohold the second rod to the main body in a slidable manner.
 2. The rodsystem of claim 1, wherein the fixation member is further mountable tothe main body to engage the portion of the first rod to hold the firstrod in the fixed manner relative to the main body.
 3. The rod system ofclaim 1, wherein the main body defines an orifice configured tointerchangeably receive the fixation member or the closure member toengage the second rod.
 4. The rod system of claim 3, wherein the orificedefines a threaded bore positioned laterally to one side of the secondrod seat, the fixation member comprises a screw with a head configuredto engage the second rod, and the closure member comprises a screw witha head that is prevented from engaging the second rod.
 5. The rod systemof claim 3, wherein the orifice is sized to substantially fully receiveeither the fixation member or the closure member in an axial direction.6. The rod system of claim 1, wherein the connector further comprises atleast one sliding member positioned in the second rod seat to facilitatesliding of the second rod.
 7. The rod system of claim 1, wherein thelongitudinal axes of the first rod seat and the second rod seat aresubstantially parallel.
 8. The rod system of claim 1, wherein at leastone of the first rod seat or the second rod seat is substantially closedaround the respective longitudinal axis.
 9. The rod system of claim 1,wherein the fixation member is a first fixation member, and wherein therod system further comprises a second fixation member, and wherein thefirst and second fixation members are respectively mountable to the mainbody to hold both the first rod and the second rod in a fixed mannerrelative to the main body.
 10. The rod system of claim 9, wherein thefirst and second fixation members are substantially similar andinterchangeably mountable to the main body for fixing the first andsecond rods to the main body.
 11. A rod system, in particular, for thespine, comprising: a first rod; a second rod; and a connector comprisinga main body for connecting the first rod and the second rod to oneanother; wherein the first rod extends from one end of the main body toan opposite end of the main body and is connected to the main body in asubstantially non-releasable manner; and wherein the main body furtherdefines a rod seat configured to hold the second rod to the main body ina slidable manner.
 12. The rod system of claim 11, wherein the connectorfurther comprises a fixation member that is permanently mountable to themain body and that is configured to act on the first rod to fix thefirst rod to the main body in the substantially non-releasable manner.13. The rod system of claim 12, wherein the fixation member comprises apin.
 14. The rod system of claim 11, wherein the main body and the firstrod are monolithically formed with one another.
 15. The rod system ofclaim 11, wherein the connector further comprises a closure member thatis mountable to the main body to hold the second rod in the slidablemanner relative to the main body
 16. The rod system of claim 15, whereinthe connector further comprises a fixation member that isinterchangeable with the closure member and mountable to the main bodyto hold the second rod in a fixed manner relative to the main body. 17.The rod system of claim 11, wherein the first rod extends along a firstlongitudinal axis relative to the connector, and the second rod isconfigured to extend and slide along an axis that is substantiallyparallel to the first longitudinal axis relative to the connector.
 18. Aconnector for connecting at least two rods, the connector comprising: amain body defining a first rod seat that extends along a firstlongitudinal axis and that is configured to hold a first rod, a secondrod seat that extends along a second longitudinal axis and that isconfigured to hold a second rod, and a threaded orifice positionedbetween the first rod seat and the second rod seat; and a fixationmember engageable with the orifice and comprising a threaded portion anda head that is wider than the threaded portion, wherein when the head isrotated, the head is movable axially relative to the main body such thata lower side of the head is configured to engage and hold both the firstrod in the first rod seat and the second rod in the second rod seat in afixed manner relative to the main body.
 19. The connector of claim 18,wherein the fixation member is formed monolithically.
 20. The connectorof claim 18, wherein the fixation member is tiltable around an axis thatis substantially parallel to the first and second longitudinal axes.